1. Technical Field
The present invention relates to a sheet sorting device configured to sort sheets discharged from an image forming device by stacking the sheets alternately at a first sheet stacking position and a second sheet stacking position.
2. Related Art
The image forming device is capable of forming images on sheets by using a printing device, such as an inkjet printer, a stencil printing device or a laser printer, a copier or the like, and performs printing or copying on many sheets. There are proposed various sheet sorting devices which can sort such a large number of sheets discharged from the image forming device, for example, into multiple sets of a predetermined number of sorted sheets or can sort and stack sets of sheets for respective jobs on a sheet receiving tray.
As one of such sheet sorting devices, Japanese Patent Application Publication No. 2008-201590 proposes a sheet receiving device capable of sorting of many sheets in an orderly manner.
Although an illustration is omitted herein, a first embodiment of the sheet receiving device (sheet sorting device) disclosed in Japanese Patent Application Publication No. 2008-201590 includes a sheet receiving tray, a contacting guide plate (offset guide plate), a stopping guide plate (end fence plate), a pair of width guide plates (pair of side fence plates), and a sheet receiving tray control means. The sheets sequentially discharged from a sheet discharging unit of a sheet processing device are stacked on the sheet receiving tray. The contacting guide plate is installed below the sheet discharging unit of the sheet processing device to be movable to offset positions, and aligns rear ends of the sheets in a sheet discharging direction. The stopping guide plate is provided to face the contacting guide plate at an interval equal to the length of the sheets and is suspended to be movable to offset positions, from a sheet receiving cover provided above the sheet receiving tray. The stopping guide plate aligns front ends of the sheets in the sheet discharging direction. The pair of width guide plates are suspended from the sheet receiving cover to be movable in a sheet width direction orthogonal to the sheet discharging direction, and align both side ends of the sheets in the sheet width direction. The sheet receiving tray controlling means lifts down the sheet receiving tray with progress of the stacking of the sheets onto the sheet receiving tray.
In the first embodiment of the sheet receiving device described above, sorting of sheets is performed in such a way that the sheets sequentially discharged from the sheet discharging unit of the sheet processing device are made to fall to the sheet receiving tray and are stacked alternately at a first sheet stacking position and a second sheet stacking position. On the sheet receiving tray, the first sheet position is set to be on the upstream side in the sheet discharging direction and the second sheet stacking position is set to be offset downstream of the first sheet stacking position by a predetermined amount. In the sheet sorting, after the completion of the sheet sorting at the first sheet stacking position (or the second sheet stacking position), the sheet receiving tray is temporarily lifted down before the contacting guide plate and the stopping guide plate are offset to a front side (or a rear side) in the sheet discharging direction by the predetermined amount to serve for the second sheet stacking position (or the first sheet stacking position). Then, the sheet receiving tray is lifted up after the contacting guide plate and the stopping guide plate are offset. Thus, the top sheet among the sheets stacked on the sheet receiving tray does not come into contact with either of the contacting guide plate and the stopping guide plate when the contacting guide plate and the stopping guide plate are offset. Accordingly, the contacting guide plate and the stopping guide plate can be surely offset by the predetermined offset amount alternately to the rear side or the front side in the sheet discharging direction.